<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script type="text/javascript">
    function sum(x,y) {
        console.log(x+y);
        //arguments里面存储的是实际参数，实际参数有几个，argument里面就存储几个值
        //Arguments是一个类似数组但不是数组的对象，还具有length属性
        console.log(arguments.length);
        //instanceof 验证某个对象是否隶属于另外一个对象
        console.log(arguments instanceof  Object);//true
        console.log(arguments instanceof  Array);//false
    }
    sum();
    sum(10,20);
    sum(10,20,30);
    var m={name:"小黄"};
    var n=[10,20];
    var x=1;
    var y="abc";
    var z=true;
    var w={};
    var g;
    var e=function () {

    };
    console.log(typeof m);//object
    console.log(typeof n);//object
    console.log(typeof x);//number
    console.log(typeof y);//string
    console.log(typeof z);//boolean
    console.log(typeof w);//object
    console.log(typeof g);//undefined
    console.log(typeof e);//function
   //数据类型：number string boolean null undefined object array  function 8种
    //typeof 返回几种数据类型----6种




</script>
</body>
</html>